An enrichment method was used to enrich functional bacteria in continuous fluid using porous carrier, which simulated dynamic environments. This method was developed based on the theory of enrichment culture and medium retain manner technique. Four bacteria strains were isolated from sewer using benzo[a]pyrene (BaP) to provide energy and carbon, among them a single strain of bacteria isolated, identified as Acinetobacter sp. Bap30 according to 16S rRNA gene sequence and identification of its physiological and biochemical characteristics, grew in mineral salt medium with 40 mg/L BaP and degraded 28.7% BaP after 20 days of incubation. The BaP-degradation function of Acinetobacter genus has not been previously reported in the literature. Addition of extra carbon sources (in particular sucrose) and phenanthrene (a low molecular weight polycyclic aromatic hydrocarbon) influenced the degradation rate, which was effectted by the type and concentration. The present study is of practical importance in environmental engineering, given that BaP is a highly toxic polycyclic aromatic hydrocarbon (PAH) commonly found in petroleum-polluted soil and industrial discharges such as coking wastewater.